Mechanically actuated reciprocating tool



Jan. 19, 1932, c. H. VIDAL MECHANICALLY ACTUATED RECIPROCATING TOOLFiled March 27, 1930 3 Sheets-Sheet l AT T9489( 'n @Y l/,/ A

Jan 19, 1932- I c. H. VIDAL LMZJZ MECHANICALLY ACTUATED RECIPROCATINGTOOL Filed March 27, 1930 3 Shreets--Shee 2 ATTORNEY Patented Jan. 19,1932 UNITED STATES PATENT OFFICE errantes HENRY VIDAL, or ennnannscnoss, :ENGLAND l MECHANICALLY ACTUATED RECIPROCATING Toor.

" npllicatian eigenaren 27, 193e, seriarNo.43s,as2, and in Great BritainFebruary 4, 1930.

This invention relates to mechanically driven reciprocating tools suchas percussion drillsyhammers, riveters and the likelof the kindin-which` the energy required `for striki ingtheblow is accumulated in aspring or springsiconsequenton the relative' rotation oftwogeared'membersone of which is continuously rotated vfrom any suitablepower source;` i i Y According to the present invention the resistanceoffered by a spring or springs to rotation of one of the pairof gearedmem-1k bers causes one member to ride .or roll along the other, and in`so doing to accumulate 1f energyin the spring or springs, this energy'being freleased to strike `.the blow when onel of the members passesthrough a. position of unstable equilibrium which is reachedsimultaneously with the tensioning lof the spring `or` springs to themaximum extent."

tion, the action `ofthe Imechanism is controlled by a device, suchasaworm fwheel provided with aI` crank (or alternatively a cam` oreccentric), connected with a subsidiary spring,ithe reactionof which isused to compress; and thus store l additional energy iii,"a secondspring `which for convenience will be called the mainfspring and which3o furnishes 4part of the energy for driving the tupv or striker. Thisdevice constitutes not only an energizing mechanism but laiso anautomatic releasing mechanism 4by reason of the fact that the wormwheel, after being rotated through approximately 180O by a worm shaftdriven from the source of power, during .which rotation the full amount'of energy is stored in both springs` (main and subsidiary)A and the tuphas beenmoved to 4e outil-shock along the cworm-shaft during the on thetool is limited only bythe inertia of ..45 the parts concerned.`

i ing exactly the same strength however the In one embodimentof thepresent inven-` itsi extreme back position, rolls freely with` The sameresults may be obtained Vby substituting forv the worm and worm wheeldevice equivalent mechanism, such as an endlesschain in conjunction withan ordinary sprocket wheel operating as a crank, or by a reciprocatingrack meshing" with a gear wheel driven by the 'primary rotating powerelement.

' In an apparatus according tothe present invention oscillations; due torebound cannot damage the mechanism in any way, and it ispossihle toarrest the stroke of the tu at any point `of its travel and hold it`there for any length of time without straining themechanism oroverloading the motor or other source of power.

A1 further advantage of the apparatus is that it is not affected byvariations in speed of the driving motor, each blow havnumber of blowsper unit time may vary in accordance with the speed of the drivingmotor, and it is possible therefore to operate the hammer perfectlysatisfactorily over a wide range of speeds.

.It will be seen that the use of ratchets, links, clutches or similardevices for interruptingthe relation of the driving means with tupduring working is obviated in mechanism according to the presentinvention, and that there is no lost motion at any time, so thatduringoperation the mechanical parts areinot subjected to abnormal shock orload.

One' embodiment of the invention is illus- 30 trated by way of examplein Figs. l and 2 of the accompanying drawings, wherein Figl is alongitudinal section of a mechanical hammerof a portable type drivenbyan electric motor, Fig, 2 being a section on line 252 of Fig. llooking in the direction of the arrows.

Figure 3 is anelevation, partly insection, of ,an embodiment of theinvention `as applied to a forge hammer.

Figures 4 and 5 are, respectively, central sectional views, in planes atright angles to one another, of a further embodiment of the invention.

Figure 6 is a longitudinal sectional view of a portable hammer orpercussion tool containing a further embodiment of the invention.

Figure 7 is a section on the line VII-VII, Figure 6.

Figure 8 is a detail sectional view of a modified means for effectinginitial compression of the subsidiary spring shown in Figure 7.

Within a casing A there is mounted an electric motor of any suitabletype havingaii armature or rotor A2 and a field magnet system A', thecasing being preferably provided with a grip handle A and a triggerswitch Ai controlling the operation of Vthe motor. The motor drives,either directly or, as shown in Fig. l, through suitable gearing G', G2,a worm lV which is journalled in bearings E, E supported in a casing Bwhich serves to .enclose all the working parts of the mechanism apartfrom the driving motor. A fan F on the motor shaft is made exceptionallyheavy so as to function not only as a cooling fan but Yalso as a4flywheel to mini- 'Y miZe variations i-n torque.Y The worm shaft ispreferably provided with an end thrust bearing Y Iadapted to deal withend loads in both-` directions set up during operation.

Mesliing Vwith the worm W is a worm wheel YV, thel journals C', C2 ofwhich have bearings formed in the tupor striker D and which projectsthrough a slot B2 in the casing B to engage the worm. A crank C on theworm wheel 7 is coupled by means of a connecting rod C3 and pin P with apiston P sliding .in a` cylinder H which is integral with or rigidlysecured to the tup D. The latter has a free sliding tit in the casing Bwhich preferably has a steel or cast iron liner B providing a suitablerwearing surface, since the casing itself for reasons of lightness wouldusually be made of aluminum.

Cooperating with the tup D, which is shown in Fig. 1 in its strikingposition, is a. main storage spring S which is initially compressedbetween the tup and the fixed casing to an extent sufficient to avoidappreciable loss of power during the working eX- tension. A

In opera-tion the worm W', which is continuously rotated by the drivingmotor so` long as the latter is in action, rotates the worm Wheel W in acounter-clockwisedirection, as viewed in Fig. l, this rotation be- -ingresisted by a spring S' which is compressed between the piston P and aplug H" closingthe end of the cylinder H. The reaction of the spring Sis definitely proportioned to the reaction of the main spring S,

having regard to the ratio between the radius of the crank C and thepitch diameter of the worm wheel W, so that the worm W' will, whiletending to compress the subsidiary spring S by means of the crank C,connecting rod C3 and piston P, also push back the tup D, thuscompressing and storing up energy in the main spring S, as well as inthe subsidiary spring S' which, during the backward movement of the tup,will be compressed a proportionate amount. Backward movement of the tupand compression of the spring will continue until the crank C passes thedead'center, i. e. after rotating through an angle of 180 from theposition shown, whereupon the energy stored in the springsl duri-ng thebackward movement of the tup is vautomatically released and the twosprings operate in' unison to drive the tup. forwardly to strike theblow, the worm wheel VVrolling freely along the worm W' at a speedvgreatly in excess of its normal speed .of travel dueto rotation by theworm. The main spring S acts directly on the tup D, causing it to moveforwardly with great velocity, but the subsidiary spring' S' will also,by reaction through the worm wheel W, assist the main spring to urge thetup forwardly. l l

The blow of the tup will be taken by the transmitter or tool holder Twhen the tup reaches the point X, but should the hammer be operatedwithout a tool, or should the resistance to lthe tup be insufficient toabsorb the blow, then the tup will overrun its normal stroke and theblow will be absorbed by a buffer spring S2, the reaction of which willcause the tup to rebound, thus returning energy to the strik-ingmechanism and relieving thedriving motor of the full duty of completingthe next cycle, as would have been necessary if the energy of the blowhad been fully absorbed by work done on the materiall which is beingdealt with. It could be arranged for the main spring S to absorb theoverrun of the tup D, but for convenience and to save space itispreferable to use a short buffer spring such as S2 of greaterstrength, so that the overrun can be checked in a shorter distance.

It will be observed, moreover, that when the tup overruns its normalstroke,.tlie crank C will rotate to a position beyond its normal initialposition, as shown in Fig. l, and in so doing will partly compresssubsidiary spring S', thus imparting useful energy to the mechanism andreducing the power-consumption required to complete the succeedingcycle.

The tupv has bearing or sliding' surfaces D', D2 and is prevented fromturning about its own axis by the end faces of the worm wheel WV whichare constrained by but are free toturn or slideat the points Z', Z2 inthe slot B2 provided in the liner B to permit its longitudinalmovement..

`It is ffl Y against the `piston P, while the other end The casing B ispartly filled with lubri` casing with the correctamount of oil. Oil

leakage is prevented bythe accurate lit of the transmitter T at thefront of the hammer, while the long `bearing E on the driving end of theworm W prevents escape of oil at this point. Noleakage of oil ispossible at any other point,

. In principle and in its main features the construction of Fig. 3 doesnot diiier from the` construction of Fig. 1. The main differ-` ence isthat the worm W reciprocates with the tup D, while the` worm wheel `W isjournalled in fixed bearingscarried by the main frameorstandard A of thehammer.

The worm shaft is splined in the boss of a pulley A", `so that, while itis rotated by the pulley, it is also free t0 slide through the pulley inthe axial or longitudinal direction. The pulley A may be driven by anysuitable means, as by belting, from an electric motor A mounted on thestandard A. c

. The tup D has a hollow body or barrel D0 which encircles the worin .VVand which is slotted along one side to receive the worm wheel lVlandpermit longitudinal movement of the tup. i

`The worm shaft is journalled in bearings E, E at the'two endsof the tupbody and collars E on theworm shaft embrace the bearing block E so as toconstrain the tup and worm shaft to move together longitudinally while`permitting rotation of the shaft with respect to the tup which isguided S so that it can only move longitudinally.

As in the case of Figures l and 2, a crank C on the worm wheel isconnected by means of connecting rod C3 and pin P with a piston Psliding in acylinder which in this case is stationary andwhich containswhat has been called the subsidiary spring S. The other spring S, whichhas been called the main spring, is compressed between the upper end ofthe tup body and the casing. to be understood, however, that one springis just as `important as the other in the operation of the hammer andthe terms main and subsidiary are merely used to differentiate betweenthem.`

One end of the subsidiary spring S abuts abuts against a follower plateor cap H0 which can be moved longitudinally within i co` sion `of thespring.

the cylinder H, as by means of a rack H on the outside of the cap and apinion H2 actuated by hand lever H3, thereby providing `means forvarying the initial compresi In. operation the continuously rotatingworm W drives the worm`wheel W, but

owing to the resistance of spring S the ro-r tation of the worm wheel isretardedand in one arm of the `swinging consequently the worm W ridesupwardly on the worin wheel and the spring S is cony sequentlycompressed. The upward movement of the tup and the compressionof thesprings S, S will cease `when the crank C passes the dead point, i. e.when it has been rotated through 180 in the clockwise direcv tion fromthe` position shown, and by varying the intial compression of the springS by means of the lever H3 the extent of the upward movement of the tup,i. e. the length of the stroke of the hammer, can be varied as desired.e

When the crank C has passed the dead point, the rotation of the wormwheel will be accelerated beyond normal speed by the reaction ofspringS, and the worin shaft and tup will be vdriven downwardly tostrike a blow, the energy of which is contributed to by both springQS,S, as well as by the weight of the tup.

The variation in the length of the stroke of the tup may be controlledby a treadle instead of by the hand lever H3, and the cylinder H and.its accessories may conveniently be accommodated within the hollowstandard of the hammer.

In Figures 4 and 5 the tup D is shown as rigid with a swinging frame Dfree on a shaft W0 which is rotated continuously from any suitablesource of power and whichhas keyed on it a spur wheellV gearing with apinion WV. The latter is freely rotatable on a stub shaft S0 which ispinned frame Do and to which is attached one end of the main springwhich is in the forni of a iat spiral spring contained within a fixedcasing encircling the shaft W0. i

The other arm of the swinging frame is connected by means of a helicalspring S with a. crank pin C on the pinion W.

When the wheel W is driven in the clockwise direction, as indicated inFig. 4, the rotation of the pinion Wr in the countenclockwise` directionwill be resisted by the spring S and thepinion will therefore be carriedazound the shaft W0 `with the spur wheel sion of spring S will beincreased Conse quently, the swinging `frame D0 will be `rocked upon theshaft W in the saine direcpinion is displaced and the tup tion as the Dwill be retracted from the transmitter or tool holder T. Simultaneouslyenergy will be stored up inthe main spring S.

The rolling movement of the pinion W on the spur wheel W (and also theswinging movement of the frame Do on the shaft W0, unless the frame isarrested by a stop) and the tensioning of the springs will continueuntil the pinion, by rotation about its own axis in thecounter-clockwise direction, ras

brought the crank pin C past the dead cen ter, i. e; 180? from theposition `shown in in the clockwise direction and the ten-` Fig. 4,whereupon the venergy stored in the springs operates to swing the frameDo in the forward or counter-clockwise direction and `'the'tup Ddelivers the blow to the transmitter or tool holder T.

In the embodiment of the invention shown 'in Figures 6 and 7 the worinshaft W0 is shown as splined into the made hollow and carries whichgears with a worm wheel TW journalled in the iXed frame B. The wormshaft W0 is shown as being driven directly by the electric motor A, A2which is enclosed in the casing A and has on its armature shaft a fan Fwhich is made heavy so as to function also as a flywheel.

Cranks C on discs rigid with the worm wheel are coupled by comiectingrods C3 with a piston l? sliding in a cylinder or guideway H containinga spring S which is adapted to be compressed between the piston and aslidable abutment H". This slidable abutment is connected with thehandle A3 by means of a link A5 and the handle is pivoted at A6 to thecasing A. Pressure tup D which is the worm iV on the handle A3 towardthe motor casing A tends to force the slidable abutment H forwardly tocompress the spring S, so that the initial force of the spring (andconsequently the force of the blow) is automatically increased as thetool is pressed against the work.

Other parts of the apparatus are designated by the same referencecharacters as the corresponding parts inthe construct-ion of Figs. l and2. Y

In operation the tup and worm are continuously rotated in one direction,and,'since the worm wheel is continuously in mesh with the worm, thewheel would be rotated continuously at the normal speed correspondingwith the gear ratio if the spring S were absent and nothing wouldhappen. The resista ce of the spring S', however, resists rotation ofthe worin wheel W, with the result that the worin WV travels backwardlyrelative to the worm wheel along the worm shaft in the manner of a rackand pinion, thereby compressing the main spring S. When the backwardmovement of the tup D is completed consequent upon the crank pins Chaving passed the dead point 180O from the position shown in Fig. 6, thetup D is driven forwardly under the action of the springs S, S to strikea blow on the transmitter or tool holder T. During the forward movementof the tup it will, of course, also be rotating, and as the rotation ofthe worm wheel W7 is accelerated by the action of the spring S, theforce of the latter assists that of the spring S in driving the tupforward.

Instead of varying the initial co-mpression of the spring Sautomatically according to thevpressure applied to the handle A3,

the'latter maybe fixed and the initial compression of the springdetermined by a plug H screwing into the end of the cylinder or guidewayH, as shown in Figure 8. As previously explained in connection with theother embodiments of the invention, the variation of the initialcompression of the spring S has the effect of varying the power of theblow end, when no back-stop is used, varying also the length of thestroke.

lt is obvious that in some of the constructions hereinbefore describedmore than one worm wheel (or the equivalent pinion.) may be provided,each being subject to the control of a spring such as S, and'whenprovision is made for the adjustment of these springs such provision mayenable them to be independently adjusted, or to be simultaneouslyadjusted.

ltv is to be understood that any or all of the springs referred to inthe various embodiments ofthe invention described above may be replacedby suitable mechanical equivalents such a pneumatic cushion, oi in somecases even by a weight. indeed, the spring S, which has been called themain spring, could be eliminated altogether, and in this case a backstop (which may be a short spring buffer stop) is provided to arrest thebackward stroke of the tup, the energy of the blow being in this casederived from the spring S.

Having thus described the nature of the said invention and the bestmeans I know of carrying the same into practical effect, I claim l. Amechanical impact device of the character described, comprising a tupmember, a power storage system which includes a spring, a continuouslyrotating shaft, two geared members driven therefrom, one of said membersbeing movable to and fro with the tup member, and an eccentric devicecarried by one of the said geared members, said eccentric device beingconnected with said spring and operating to energize same upon rotationby the continuously rotating shaft of the geared member by which saideccentric device is carried.

2. A mechanical impact device of the character described, comprising atup member, a continuously rotating shaft, two rotatable geared membersdriven therefrom, o ne of said geared members being movable to and frowith the tup member, a spring adapted to be energized during one periodof the said movement, a second spring, an eccentric member on one ofsaid rota-table geared members, and a device connecting the saideccentric with the said second spring and operating to energize the saidsecond spring during a period of one half revolution of the said gearedmember about its axis.

` character described, comprising a tup nicmber, a power storage systemwhich includes a spring, a continuously rotating shaft, two gearedmembers driven therefrom, one of said members being movable to and frowith the tup member, an eccentric device carried by one of the saidgeared members and connected with said spring, and means for varying theinitial set of said spring.

4. In a mechanical impact device the combination of a reciprocatabletup, yielding means constantly urging the tup in the striking direction,adriving element for retracting the tup against the action of saidyielding means, and operative connections between the driving elementand the tup, said connections comprising a thrust-abutment to receivethe retracting force or its reaction, and a yielding toggle supportingsaid abutment adapted to give way under a predetermined pressure and letthe tup advance freely.

5. A mechanical impact device as claimed in claim 4-,wherein the thrustabutment is constituted by the meshing portion of a wheel geared withthe driving element so as to be actuated thereby and the yielding toggleis constituted by a yielding link engaged with a crankon the gear wheel.

6. A mechanical impact device as claimed in claim 4, wherein the thrustabutment constituted by the meshing portion of awheel geared with thedriving member s0 as to be actuated thereby and the yielding toggle isconstituted by a spring-pressed connecting rod engaged with a crank onthe gear wheel.

7. In a mechanical impact device the combination of a reciprocatabletup, yielding means constantly urging the tup in the striking direction,driving means for retracting the tup against the action of said yieldingmeans, said driving means comprising a driving element having a meshingportion,

a wheel geared with the meshing portion oi` the driving element so as tobe actuated thereby, a crank on the gear-wheel and a yielding link whichtransmits retracting force from the crank to the tup and constituteswith the crank a yielding' toggle so as to give way under apredetermined pressure and let the tup advance freely.

8. A mechanical impact device as claimed in claim 7 wherein thegear-wheel is itself mounted to reciprocate with the tup.

9. A mechanical impact device as claimed in claim 7 wherein thegear-wheel is mounted separately from the tup to rotate about a fixedaxis and the driving element engages the tup on the one hand and thegear-wheel on the other to thrust the tupI rearwardly relatively to thegear-wheel.

l0. A mechanical impact device as claimed in claim 7 wherein the drivingelement comprises a rotatable worm set with its axis parallel to that ofthe movement of the tup, the gear-wheel is a worm wheel and one of theseparts is disposed upon the tup to reciprocate therewith.

11. A mechanical impact device as claimed in claim 7 wherein theyielding link comprises a spring-pressed connecting rod.

In testimony whereof I have signed my name to this specification.

CHARLES HENRY VIDAL.

